James Paces
Primary research responsibilities includes collection of radiogenic isotope data (U-series and Sr) used to date Quaternary deposits and provide natural tracers of mass flow through near-surface environments.
EMPLOYMENT HISTORY
Scientist Emeritus, USGS, Geology and Environmental Change Science Center, (2021-)
Research Geologist, USGS, Geology and Environmental Change Science Center, (2010 - 2020)
Geochronological and radiogenic isotope studies associated with 1) Quaternary landscape evolution for Geologic-Mapping Studies at Buffalo National River, AR; Greater Platte River basin, CO; Rio Grande Rift, NM & CO, 2) probabilistic seismic hazard analyses, eastern WA, 3) Pleistocene water-table fluctuations and aquifer sources at Wind Cave NP, SD, 4) ages of megafauna and archaeological sites, CO & CA, 5) hydrologic sources and mixing in modern and paleohydrologic environments (Pahranagat NWR, NV; Sacramento-San Joaquin Delta, CA; Yellowstone NP, WY; Gallatin Valley, MT; upper Santa Cruz River basin; AZ), 6) structural evolution of Channel Islands NP, CA, 7) timing of U mineralization, TX & VA.
Research Hydrologist, USGS, Yucca Mountain Project Branch, (1992 - 2010)
Geochemical and isotopic characterization of the Nation’s proposed high-level radioactive waste repository at Yucca Mountain, NV. Studies of both surface- and subsurface-based geochronology, hydrology, and paleoclimate investigations using Sr and U-Th isotopes to characterize modern and Pleistocene hydrologic processes.
Geologist, Natl. Res. Council Post-doc, USGS, Branch of Isotope Geology (1990 - 1991)
1) Isotopic (U-Pb, Rb-Sr, Sm-Nd) investigation of lower crustal nodules from Jurassic kimberlites, MI, 2) High-precision, single-zircon U-Pb dating of 1.1 Ga mafic intrusions in the Duluth Complex, MN.
Geologist, Post-doc fellow, Univ. Tennessee (1989)
Sr- and Nd-isotope study of whole rocks and mineral separates of Apollo 17 mare basalts.
EDUCATION
Ph.D. in Geology, Michigan Technological University, Houghton, Michigan, 1988; Magmatic processes, evolution and mantle source characteristics contributing to the petrogenesis of Midcontinent Rift Basalts: Portage Lake Volcanics, Keweenaw Peninsula, MI
B.S. in Geology (with honors), University of Oregon, Eugene, Oregon, 1978
AWARDS
USGS Superior Service Award, 2005
GSA Fellow
Colorado Scientific Society President, 2020
PROFESSIONAL AFFILIATIONS
Geological Society of America
American Geophysical Union
Geochemical Society
International Association of Geochemistry
Science and Products
Filter Total Items: 20
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Evaluation of groundwater movement in the Frenchman Flat CAU using geochemical and isotopic analysis
The principal pathway for radionuclide migration from underground tests in Frenchman Flat, on the Nevada Test Site, to the accessible environment is groundwater flow. Two potential pathways for radionuclide transport via groundwater have been identified from hydrologic data: (1) radionuclide transport downward from the alluvial and volcanic aquifers into the underlying carbonate aquifer...
Authors
R. L. Hershey, J. M. Thomas, T. P. Rose, James B. Paces, I. M. Farnham, F. C. Benedict
Geochemical and C, O, Sr, and U-series isotopic evidence for the meteoric origin of calcrete at Solitario Wash, Crater Flat, Nevada, USA
Calcite-rich soils (calcrete) in alluvium and colluvium at Solitario Wash, Crater Flat, Nevada, USA, contain pedogenic calcite and opaline silica similar to soils present elsewhere in the semi-arid southwestern United States. Nevertheless, a ground-water discharge origin for the Solitario Wash soil deposits was proposed in a series of publications proposing elevation-dependent variations...
Authors
Leonid A. Neymark, James B. Paces, B.D. Marshall, Z. E. Peterman, J. F. Whelan
U-Series isotopes as indicators of water/rock interaction in the unsaturated zone at Yucca Mountain, Nevada, USA
No abstract available.
Authors
James B. Paces, Leonid A. Neymark
Weathering of the meade peak phosphatic shale member, phosphoria formation: Observations based on uranium and its decay products
Variably weathered outcrop samples of the Meade Peak Phosphatic Shale Member of the Phosphoria Formation have 5-10% of the contained uranium (U) in a form readily extractable by 0.1 M sodium bicarbonate. Fission track radiography of outcrop samples and other less-weathered channel and core samples indicate that this mobile fraction of U is likely hosted by organic matter, secondary iron...
Authors
Robert A. Zielinski, James R. Budahn, Richard I. Grauch, James B. Paces, K. Rogers Simmons
Reply to the comment on “Physical and stable-isotope evidence for formation of secondary calcite and silica in the unsaturated zone, Yucca Mountain, Nevada”, by Y.V. Dublyansky, S.E. Smirnov and G.P. Palyanova
No abstract available.
Authors
Joseph F. Whelan, James B. Paces, Zell E. Peterman, Brian D. Marshall, Leonid A. Neymark
Improved spatial resolution for U-series dating of opal at Yucca Mountain, Nevada, USA, using ion-microprobe and microdigestion methods
Two novel methods of in situ isotope analysis, ion microprobe and microdigestion, were used for 230Th/U and 234U/238U dating of finely laminated opal hemispheres formed in unsaturated felsic tuff at Yucca Mountain, Nevada, proposed site for a high-level radioactive waste repository. Both methods allow analysis of layers as many as several orders of magnitude thinner than standard methods...
Authors
James B. Paces, Leonid A. Neymark, J. L. Wooden, H.M. Persing
Quaternary paleoseismology and stratigraphy of the Yucca Mountain area, Nevada
No abstract available.
Authors
John W. Whitney, Emily M. Taylor
Reliability of U-Th-Pb dating of secondary silica at Yucca Mountain, Nevada
No abstract available.
Authors
Leonid A. Neymark, James B. Paces, Y. V. Amelin
U-series disequilibrium as a test for unsaturated-zone hydrologic models at Yucca Mountain, Nevada
No abstract available.
Authors
James B. Paces, Leonid A. Neymark
Summary of Chlorine-36 validation studies at Yucca Mountain, Nevada
No abstract available.
Authors
James B. Paces, Zell E. Peterman, Leonid A. Neymark, G. J. Nimz, Mel Gascoyne, Brian D. Marshall
Geochemistry of dust in the Exploratory Studies Facility, Yucca Mountain, Nevada
No abstract available.
Authors
Zell E. Peterman, James B. Paces, Leonid A. Neymark, D. Hudson
Pliocene to Holocene Lakes in the Western Great Basin, USA: New perspectives on paleoclimate, landscape dynamics, tectonics, and paleodistribution of aquatic species
No abstract available.
Authors
Marith C. Reheis, Joanna R. Redwine, K. Adams, S. Stine, K. Parker, R. Negrini, R. M. Burke, G. Kurth, John P. McGeehin, James B. Paces, F. M. Phillips, Andrei M. Sarna-Wojcicki, J. P. Smoot
Non-USGS Publications**
Paces, J.B., Nakai, S., Neal, C.R., Taylor, L.A., Halliday, A.N., and Lee, D-C, 1991, A Sr and Nd isotopic study of Apollo 17 high-Ti basalts: resolution of ages, evolution of magmas, and origins of source heterogeneities: Geochimica et Cosmochimica Acta, v. 55, p. 2025-2043.
Neal, C.R., Taylor, L.A., Davidson, J.P., Holden, P., Halliday, A.N., Paces, J.B., Clayton, R.N., and Mayeda, T.K., 1990, Eclogites with oceanic crustal and mantle signatures from the Bellsbank Kimberlite, South Africa, Part II: Radiogenic isotopes and geochemical evolution: Earth and Planetary Science Letters, v. 99, p. 362-379.
Davis, D.W., and Paces, J.B., 1990, Time resolution of geological events on the Keweenaw Peninsula and implications for development of the Midcontinent Rift system: Earth and Planetary Science Letters, v. 97, p. 54-64.
Paces, J.B., and Bell, K., 1989, Non-depleted sub-continental mantle beneath the Superior Province of the Canadian Shield: Nd-Sr isotopic and trace element evidence from Midcontinent Rift basalts: Geochimica et Cosmochimica Acta, v. 53, p. 2023-2035.
Zolensky, M.E., Sylvester, P.J., and Paces, J.B., 1988, Origin and significance of blue coloration in quartz from Llano Rhyolite (Llanite), north-central Llano County, Texas: American Mineralogist, v. 73, p. 313-323.
Bornhorst, T.J., Kalliokoski, J., and Paces, J.B., 1986, The Keweenaw Native-Copper District, in Brown, A.C., Kirkham, R.V. (eds.), Proterozoic Sediment-hosted Stratiform Copper Deposits of Upper Michigan and Belt Supergroup of Idaho and Montana: Geological Association of Canada/Mineralogical Association of Canada/Canadian Geophysical Union Joint Annual Meeting, Ottawa '86, Field Trip 1 Guidebook, p. 21-36.
McDowell, S.D., and Paces, J.B., 1985, Carbonate alteration minerals in the Salton Sea geothermal system, California, USA: Mineral Magazine, v. 49, p. 469-479.
Wilson, M.L., Paces, J.B., and Ruotsala, A.P., 1984, Fluorapatite from the King Lithia mine, Custer County, South Dakota: Mineral Record v. 15, p. 361-366.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 20
No Result Found
Filter Total Items: 87
Evaluation of groundwater movement in the Frenchman Flat CAU using geochemical and isotopic analysis
The principal pathway for radionuclide migration from underground tests in Frenchman Flat, on the Nevada Test Site, to the accessible environment is groundwater flow. Two potential pathways for radionuclide transport via groundwater have been identified from hydrologic data: (1) radionuclide transport downward from the alluvial and volcanic aquifers into the underlying carbonate aquifer...
Authors
R. L. Hershey, J. M. Thomas, T. P. Rose, James B. Paces, I. M. Farnham, F. C. Benedict
Geochemical and C, O, Sr, and U-series isotopic evidence for the meteoric origin of calcrete at Solitario Wash, Crater Flat, Nevada, USA
Calcite-rich soils (calcrete) in alluvium and colluvium at Solitario Wash, Crater Flat, Nevada, USA, contain pedogenic calcite and opaline silica similar to soils present elsewhere in the semi-arid southwestern United States. Nevertheless, a ground-water discharge origin for the Solitario Wash soil deposits was proposed in a series of publications proposing elevation-dependent variations...
Authors
Leonid A. Neymark, James B. Paces, B.D. Marshall, Z. E. Peterman, J. F. Whelan
U-Series isotopes as indicators of water/rock interaction in the unsaturated zone at Yucca Mountain, Nevada, USA
No abstract available.
Authors
James B. Paces, Leonid A. Neymark
Weathering of the meade peak phosphatic shale member, phosphoria formation: Observations based on uranium and its decay products
Variably weathered outcrop samples of the Meade Peak Phosphatic Shale Member of the Phosphoria Formation have 5-10% of the contained uranium (U) in a form readily extractable by 0.1 M sodium bicarbonate. Fission track radiography of outcrop samples and other less-weathered channel and core samples indicate that this mobile fraction of U is likely hosted by organic matter, secondary iron...
Authors
Robert A. Zielinski, James R. Budahn, Richard I. Grauch, James B. Paces, K. Rogers Simmons
Reply to the comment on “Physical and stable-isotope evidence for formation of secondary calcite and silica in the unsaturated zone, Yucca Mountain, Nevada”, by Y.V. Dublyansky, S.E. Smirnov and G.P. Palyanova
No abstract available.
Authors
Joseph F. Whelan, James B. Paces, Zell E. Peterman, Brian D. Marshall, Leonid A. Neymark
Improved spatial resolution for U-series dating of opal at Yucca Mountain, Nevada, USA, using ion-microprobe and microdigestion methods
Two novel methods of in situ isotope analysis, ion microprobe and microdigestion, were used for 230Th/U and 234U/238U dating of finely laminated opal hemispheres formed in unsaturated felsic tuff at Yucca Mountain, Nevada, proposed site for a high-level radioactive waste repository. Both methods allow analysis of layers as many as several orders of magnitude thinner than standard methods...
Authors
James B. Paces, Leonid A. Neymark, J. L. Wooden, H.M. Persing
Quaternary paleoseismology and stratigraphy of the Yucca Mountain area, Nevada
No abstract available.
Authors
John W. Whitney, Emily M. Taylor
Reliability of U-Th-Pb dating of secondary silica at Yucca Mountain, Nevada
No abstract available.
Authors
Leonid A. Neymark, James B. Paces, Y. V. Amelin
U-series disequilibrium as a test for unsaturated-zone hydrologic models at Yucca Mountain, Nevada
No abstract available.
Authors
James B. Paces, Leonid A. Neymark
Summary of Chlorine-36 validation studies at Yucca Mountain, Nevada
No abstract available.
Authors
James B. Paces, Zell E. Peterman, Leonid A. Neymark, G. J. Nimz, Mel Gascoyne, Brian D. Marshall
Geochemistry of dust in the Exploratory Studies Facility, Yucca Mountain, Nevada
No abstract available.
Authors
Zell E. Peterman, James B. Paces, Leonid A. Neymark, D. Hudson
Pliocene to Holocene Lakes in the Western Great Basin, USA: New perspectives on paleoclimate, landscape dynamics, tectonics, and paleodistribution of aquatic species
No abstract available.
Authors
Marith C. Reheis, Joanna R. Redwine, K. Adams, S. Stine, K. Parker, R. Negrini, R. M. Burke, G. Kurth, John P. McGeehin, James B. Paces, F. M. Phillips, Andrei M. Sarna-Wojcicki, J. P. Smoot
Non-USGS Publications**
Paces, J.B., Nakai, S., Neal, C.R., Taylor, L.A., Halliday, A.N., and Lee, D-C, 1991, A Sr and Nd isotopic study of Apollo 17 high-Ti basalts: resolution of ages, evolution of magmas, and origins of source heterogeneities: Geochimica et Cosmochimica Acta, v. 55, p. 2025-2043.
Neal, C.R., Taylor, L.A., Davidson, J.P., Holden, P., Halliday, A.N., Paces, J.B., Clayton, R.N., and Mayeda, T.K., 1990, Eclogites with oceanic crustal and mantle signatures from the Bellsbank Kimberlite, South Africa, Part II: Radiogenic isotopes and geochemical evolution: Earth and Planetary Science Letters, v. 99, p. 362-379.
Davis, D.W., and Paces, J.B., 1990, Time resolution of geological events on the Keweenaw Peninsula and implications for development of the Midcontinent Rift system: Earth and Planetary Science Letters, v. 97, p. 54-64.
Paces, J.B., and Bell, K., 1989, Non-depleted sub-continental mantle beneath the Superior Province of the Canadian Shield: Nd-Sr isotopic and trace element evidence from Midcontinent Rift basalts: Geochimica et Cosmochimica Acta, v. 53, p. 2023-2035.
Zolensky, M.E., Sylvester, P.J., and Paces, J.B., 1988, Origin and significance of blue coloration in quartz from Llano Rhyolite (Llanite), north-central Llano County, Texas: American Mineralogist, v. 73, p. 313-323.
Bornhorst, T.J., Kalliokoski, J., and Paces, J.B., 1986, The Keweenaw Native-Copper District, in Brown, A.C., Kirkham, R.V. (eds.), Proterozoic Sediment-hosted Stratiform Copper Deposits of Upper Michigan and Belt Supergroup of Idaho and Montana: Geological Association of Canada/Mineralogical Association of Canada/Canadian Geophysical Union Joint Annual Meeting, Ottawa '86, Field Trip 1 Guidebook, p. 21-36.
McDowell, S.D., and Paces, J.B., 1985, Carbonate alteration minerals in the Salton Sea geothermal system, California, USA: Mineral Magazine, v. 49, p. 469-479.
Wilson, M.L., Paces, J.B., and Ruotsala, A.P., 1984, Fluorapatite from the King Lithia mine, Custer County, South Dakota: Mineral Record v. 15, p. 361-366.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.